[PATCH v4 02/59] do_fchmodat(): import pathname only once

Al Viro
2026-01-08T07:36:48Z

Convert the user_path_at() call inside a retry loop into getname_flags() +
filename_lookup() + putname() and leave only filename_lookup() inside
the loop.

Since we have the default logics for use of LOOKUP_EMPTY (passed iff
AT_EMPTY_PATH is present in flags), just use getname_uflags() and
don't bother with setting LOOKUP_EMPTY in lookup_flags - getname_uflags()
will pass the right thing to getname_flags() and filename_lookup()
doesn't care about LOOKUP_EMPTY at all.

The things could be further simplified by use of cleanup.h stuff, but
let's not clutter the patch with that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/open.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index f3bacc583ef0..82bfa06dbfa5 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -679,6 +679,7 @@ static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
unsigned int flags)
{
struct path path;
+ struct filename *name;
int error;
unsigned int lookup_flags;

@@ -686,11 +687,9 @@ static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
return -EINVAL;

lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
- if (flags & AT_EMPTY_PATH)
- lookup_flags |= LOOKUP_EMPTY;
-
+ name = getname_uflags(filename, flags);
retry:
- error = user_path_at(dfd, filename, lookup_flags, &path);
+ error = filename_lookup(dfd, name, lookup_flags, &path, NULL);
if (!error) {
error = chmod_common(&path, mode);
path_put(&path);
@@ -699,6 +698,7 @@ static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
goto retry;
}
}
+ putname(name);
return error;
}

--
2.47.3